Loss of Heat from Covered Steam Pipes 



Then, by (2) 



293 = 3-44 X 1.7 (/ 66), 



t =116. Then 1 16 66 = 50. 

 We may now find Q for 50 difference of temp. 

 ^=.75 X 1.2 X i. 02 = .916 

 A = .47 X 1.2 =-565 



1.48 

 Then M > = - 3.44X1.5(299) = 28 



/i. 5 X.548X.2\ 



+ I - J 



V -5 / 



I2 



-45 

 and t = 121.5 



It is evidently unnecessary to make another and closer 

 approximation to Q. 



It will be noticed that a difference of about twelve per cent. 

 in the value of Q only made a difference of two per cent, in the 

 results. So it is quite unnecessary to be too particular about the 

 value of Q, and the smaller the pipe the less effect does an error 

 in Q have. 



The following values of C for different materials were deter- 

 mined by Peclet : 

 Plaster ...... 3.44 Hempen Canvas. . . -4i8 - 



Oak . . . . . . . 1.70 Smooth White Paper . .346 



Walnut ....... 86 Cotton Wool ..... 323 



Fir ........ 75 Sheep Wool ..... 323 



Powdered Charcoal . . '637 Eiderdown ..... 314 



Wood Ashes ..... 484 Blotting Paper . . . .274 



As far as the theory goes it evidently makes no difference 

 whether the steam in the pipe is at rest or in motion, for the 

 inner surface of the covering is at the same temperature in either 

 case; namely that of the steam. Mr. Barrus made tests at the 

 Manhattan Railway Co.'s new power house, in which he found 

 the same rate of condensation from a covered pipe whether the 

 steam was at rest or moving with a velocity of 18 feet per sec- 

 ond. He also found this to be true for a bare pipe. (Power ; 

 Dec., 1901.) 



As this theory is of such old origin it seemed best to apply it 

 to a number of recent pipe covering tests and see how well calcu- 

 lations made by it would agree with their results. 



